Originally Posted by Lohman446
WARNING NOT A LAWYER AND GOING BY MEMORY:
Its only an issue if they are readily adapted to firearms. As these will have barrel threading on them for .68 caliper barrels and will not readily slide over the barrel of most firearms it is not "readily" adapted depending on what that term means exactly.
That's not entirely correct, and is a very common misconception.
Take a look at the A5OG and X7OG forums for more extensive discussion and research on this topic. As much as I'd like one, Doc is right. There's a risk unless it's pre-approved by the BATF.